The present invention relates to a method for manufacturing a semiconductor device, and more specifically, to a method for obtaining an overlay margin between a storage node contact plug and a storage node using a multi functional hard mask layer that serves as a hard mask as well as an anti-reflection film.
Currently, a bottom anti-reflection coating (BARC) film, which is coated by a spin-on system, contains a material that absorbs light in a particular wavelength band of an exposure light source. The BARC film is applied before a photoresist film is coated for a patterning process with KrF.
The BARC film prevents scattered reflection from beneath the photoresist film and eliminates standing waves inside the thickness of the photoresist film. This increases the uniformity of the photoresist film. However, since the BARC film does not serve as a hard mask layer, researches have been forced to develop cross-linking agents and polymers for anti-reflection films to more easily remove the BARC film.
As devices become smaller, the thickness of the photoresist film has become thinner to prevent the collapse of patterns and obtain exposure latitude (EL) and depth of focus (DOF) so that the photoresist film does not serve as an etching barrier. When an amorphous carbon layer is used as a hard mask, it requires additional processes for forming a photoresist film, an anti-reflection film, and a silicon oxide nitride film.